Center-guide for fin-stabilized fixed round ammunition



G. M. BARNES ET AL Feb. 10, 1959 CENTER-GUIDE FOR FIN-STABILIZED FIXED ROUND AMMUNITION Filed Jan. 8, 1952 INVENTORE, Glacfenn JTLJEnarnes 1121512111 R. Drnulard //l/l///I// III/rill!!! 11/ CENTER-GUIDE non FIN-STABILIZED FIXED ROUND AMMUNITION Gladeon M. Barnes, Philadelphia, and Nelson R. Droulard, Ambler, Pa., assignors to the United States of America as represented by the Secretary of the Army Application January 8, 1952, Serial No. 265,436

10 Claims. 01. 102-38) (Granted under Title 35, U. S. Code (1952), see. 266) The present invention relates to fixed round ammunition of the type, for example, which is used in breech loaded artillery weapons.

Ammunition of this type is usually spin-stabilized and though originally intended for antiaircraft defense, has since been adapted for use against ground and waterborne targets by 'virtue of the incorporation of armorpiercing and-high-explosive substances;

For certain specific purposes, experience has indicated that greaterblast propagation and more effective destruction of the selected target is obtained for finstabiliZe d rather than spin-stabilized rounds. Consequently,' whenf fins arepused the expedient of providing guide rails inthe cartridge case has been resorted to, in order (1-)i1to prevnt the tail. fins from bearing against the 'side wallsof the tapered cartridge case, (2) to guide theproj'ectile as it leaves the c'ase,iand (3) to obtain less departure of the projectile fromtrue trajectory thereby insuring less dispersion infiringi v The use of guide-Tails? to achieve the required result has'=not "been very eifective since fine machining and tolerances'for the "rai.ls and fins"are"nece ssary. Also, assembly of the case; rails 'and" projectile, being com.- plicated and time consuming, does not'len'd itself readily to mass production techniques and methods.

jltis accordingly an object'of this invention to provide a s'ubstitute for the'guider'ailswhich will not require the precise machining'a'nd tolerances needed in the guide rails; and which *will make assembly of; the eiitire round less laboriousand lesstime consuming thereby facilitating the use of' mass production methods and techniques.

It is also a further object to provide a center-guide forjthe' proje'ctile, which fits into a bore in a specially constructed'talil for a projectfle and which oifers guidance ito the-lprojectile and will remain with the cartridge case' when the projectile is fired. V I

Withtheseand other objects in View which will becomeapparent as the following specification develops, referenceis madeto the accompanying drawing which forms apartof the specification and wherein like numerals forsimilar or corresponding parts in the several views will be'us'ed.

' Fig'ure lis a plan view," partly in section of the complete assembled projectile.

Figure .2 is -a'lo'ngitudinal section of the rear end of the, projectile; showing'the cartridge case, tail and tail guide stu d assembly. a j

Figure 3v :isia fragmentary section showing the cartridge case and parts remaining after the projectile is fired Figure 4"is a'transversesection taken on line 44 of Figure; 2 a, M m 1' p Figure 5 is a section taken on line 5-5 of Figure 2.

Referring more" particularly toFigures 1 and 2 ref- 1 ;9ha ,a9 er .ignates...the..nose or forward ogive ii h 9 1 i?. l which.may.include;a fuse (not shown), Wh Q RF EF Q mm. a. .Qfillttal .bourrelet 'portion :2' tocontact the smooth bore ofa weapon. Bourrelet portion 2 in turn merges with the rear ogive 3 to which is joined in any convenient manner a boom 4, having an axial bore 5 and a plurality of transverse drilled holes 6 communicating therewith and with the space formed by the cartridge case. The rearmost portion of bore 5 is internallythreaded as at 7 to screw threadedly receive mating threads on the tail portion 8, which also acts as a hub for the fin assembly 9. The entire projectile, including the tail fin assembly is received in a forwardly tapering cartridge case 10 which contains the usual propellent charge 10b. A plastic or rubber composition sealing member 10a sealingly engages the forward end of the inner wall of cartridge case 10, and the rear ogive of the projectile. The projectile may also be provided with a high-explosive or with an amor-piercing substance, as is well known.

The center-guide assembly, as more clearly seen in Figures 2, 3 and 5, is also received in the cartridge case 10 and comprises a cast filler plug 11 having a reduced rearwardly extending central cylindrical portion 12 and a frusto-conical forwardly extending body portion 13. The base of the main body portion is provided with a pcripheral lip or protuberance 14, WhlCh'iIl assembly is pressediinto a circumferential groove 13b in an inwardly struck flange 13a formed integral with the Wall of the cartridge case adjacent the bottom of the case, to hold the center-guide assembly fast in the container when the projectile is fired. An O-ring 13c, surrounding lip 14, is received in groove 13b to provide a gas-tight seal in the well known manner. Apertures 11a are also formed in the main body portion of the cast filler plug 11 so that the propellent charge may be introduced into the case after the projectile is assembled, the rearwardly extended portion 12 being received in a central aperture 15a formed in a flat disc like closure plug 15 screw-threadedly engaging the'cartridge case wall to close off the space formed between the case wall and the filler plug extension 12 and also sealing ofi apertures 11a to prevent the propellent charge from spilling out.

Main filler plug 11 is provided with an axial bore 16' which is rearwardly stepped as at 17 to form a second axial bore 18 of smaller diameter than bore 16, and which in'turn is stepped again to form a rearmost axial bore 19 of substantially the same diameter as bore 16. Bore 16 of filler plug 11 is provided with threads to screW-threadedly receive an elongated tubular tail guide stud or center-guide 20, the rear end of which abuts step or shoulder 17, the forward end extending forwardly fora considerable length into the cartridge case along its longitudinal axis. The tail guide stud is provided with an axial bore or flash passage 21 which extends for substantially its entire length, but ending rearwardly for a short distance in a larger axial bore 22 of substantially the same diameter as bore 18 in the filler plug to aline therewith. A primer '23, as is Well known, is fitted into bores 18, 19 and 22. i

- The center-guide stud is formed with an enlarged externally threaded rear portion 24 of comparatively short length axially and a longer forward reduced portion 25 forming therebetween a step or shoulder 26. Tail 8 of the projectile is provided with a first forward axial bore or flash passage 27 extending between flash passage 21 of the center-guide stud and axial bore 5 in the projectile boom, a second axial bore 27a of diameter approximately the same or slightly larger than the outside diameter of the center-guide stud to provide a reasonably loose fit thereover when the projectile is assembled, and a third rearmost largest axial bore 28 which is threaded to screw-threadedly engage the threaded portion 24 of the center-guide stud. A rear portion 29 of the wall of Patented Feb. 10, 1959 the projectile tail, extending forwardly for a short distance from the forward face of frusto-conical filler plug 11, is reduced in diameter to provide a much weakened section at that location which will snap when the projectile is fired to release the projectile. Holes 30 may also be drilled in Weak portion 29 to provide further weakening.

In firing the projectile, primer 23 is detonated and the flash therefrom travels forwardly through flash passages 21, 27 into bore of the boom section and out of holes 6 to ignite the propelling charge. The forward force of propulsion is suflicient to cause tail 5 to snap in the vicinity of holes in weakened portion 29, whereupon the projectile is caused to travel up the bore of the weapon and out of the cartridge case. It is to be noted that tail guide stud 20 is of sufficient length to maintain the fin assembly centered in the cartridge case, and to act as a positive guide for a distance which ends just slightly to the rear of the portion where the forward taper of the cartridge case commences. Experience has shown that the projectile has sufficient impetus and has been provided with enough center guidance so that the tail fins will not bear against the tapered end of the cartridge case. The arrangement of filler plug, closing plug, cartridge .case and lip 14 cooperating with flange 13a are suflicient to retain the center guide assembly in place as the projectile moves forwardly.

Numerous other modifications and alterations of the structure which has been disclosed herein for purposes of illustration will be apparent to one skilled in the art and it is Obvious that the same may be made without departing from the spirit and scope of the invention as defined in the following claims.

We claim:

1. A center-guide for fixed ammunition comprising, a cartridge case, a fin stabilized projectile received in said cartridge case including a fin assembly comprising a tail forming a hub for said fin assembly and secured to the rear end of said projectile on one end and to the bottom of said cartridge case on its other end, said tail having an axial bore, a forwardly directed center-guide stud secured to the bottom of said cartridge case and slidably received in said axial bore, said tail having a weakened wall portion fracturable when said projectile is fired.

2. The combination in claim 1 including a propellent charge in said cartridge case surrounding said tail fin assembly, a primer located in the bottom of said cartridge case isolated from said propellent charge, said center-guide stud having an axial flash passage communicating with said primer at its rear end and with said propellent charge at its forward end.

3. In a fixed round, a device for guiding the forward travel of a fin stabilized projectile as it leaves a cartridge case comprising, a forwardly directed elongated guide stud secured to the bottom of said cartridge case and having external screw-threads adjacent said bottom, a projectile received in said cartridge case including a fin assembly secured to the tail of said projectile, said tail being provided with an axial bore having internal 'screwthreads to engage the threads on said guide stud, said tail also having a weakened wall section substantially coextensive with said internal screw-threads whereby said section fractures when said projectile is fired.

4. The combination in claim 3 including a propellent charge in said cartridge case disposed about said fin assembly, said guide stud having a rearwardly disposed axial bore and a forward axial elongated flash passage, a primer received in said axial bore, said flash passage communicating with said axial bore at its rear end and said propellent charge at its forward end.

5. In a fixed round, a device for guiding the forward travel of a fin stabilized projectile as it leaves a cartridge case when fired comprising, a forwardly directed elongated center-guide stud secured to the bottom of said cartridge case and having external screw threads adjacent said bottom, a projectile received in said cartridge case including a front ogive and rear ogive and a central bourrelet, a boom section having an axial bore and a plurality of transverse holes, merging with said rear ogive, a tail fixedly engaging said boom, a fin assembly secured to the tail of said projectile, said tail being provided with a forwardly disposed axial flash passage communicating with the bore in said boom at its f rward end and enlarging into a rearward elongated axial bore having internal screw threads at its rearmost end to engage the external threads on said guide stud, said center-guide stud having an elongated flash passage alined with the flash passage in said tail and enlarging into .a rearwardly disposed axial bore, a primer received in the bore in said center-guide stud, a propellent charge in said cartridge case disposed about said tail fin assembly and said boom, said tail section also having a weakened wall substantially coextensive with said internal screw threads whereby said section fractures when said projectile is fired.

6. In a fixed round a device for guiding the forward travel of a fin stabilized projectile as it leaves a cartridge case comprising, a cartridge case, a fusiform projectile received in said cartridge case and having a fin assembly including a tail forming a hub for said fin assembly secured to the rear end of said projectile on one end and to said cartridge case on its rear end, said tail having an elongated axial 'bore, means secured to the bottom of said cartridge case and slidably engaging the peripheral wall of the bore in said tail to guide said projectile when said round is fired, said tail having a weakened wall adjacent the bottom of said cartridge case fracturable when said projectile is fired to release the same.

7. The combination in claim 6 including a propellent charge in said case disposed about the rear end of said projectile, a primer in the bottom of said case isolated from said propellent charge, and means forming a flash passage in said projectile guiding means communicating at one end with said primer and at the other end with said propellent charge.

8. A fixed round comprising, a casing having a base, a tubular stud fixed centrally of said base and extending forwardly and centrally along said casing, a fin-stabilized projectile including a tubular tail portion slidably fitting said tubular stud, and a rigid connection between said stud and tail portion adjacent said base, said tail portion having a frangible section immediately forward of said connection.

9. A fixed round including a cartridge case having a base, a fin-stabilized projectile received in said cartridge case, and means for guiding said projectile centrally within said case pri r to expulsion of said projectile from said case and comprising, an elongated tubular stud fixed centrally of said base and extending forwardly substantially to the forward end of said fins and centrally of said case, said projectile having a tubular tail portion providing a sliding fit with said stud, and a rigid connection between said stud and said tail portion adjacent said base, said tail portion having a frangible section immediately forward of said connection.

10. The combination in claim 9 including a propellent charge in said cartridge case, a primer received in said cartridge case and isolated from said propellent charge, said tail portion having means including an axial flash passage communicating with said primer at its rear end and with said propellent charge at its forward end.

References Cited in the file of this patent FOREIGN PATENTS 504,055 France Apr. 2, 1920 83,405 Sweden May 14, 1935 373,378 Italy July 25, 1939 

